The subject matter disclosed herein relates to turbines and turbo-machinery, and more particularly, to inter-stage seals in such turbines.
Turbine components, especially in gas and steam turbine systems, may be directly exposed to high temperature fluids, and therefore require cooling to meet their useful life. For example, some of the compressor air is diverted from the combustion process for cooling rotor components of the turbine.
The main flow path of a turbine is designed to confine the main working fluid as it flows through the turbine. Turbine rotor structural components are generally provided with cooling fluid independent of the main working fluid flow to prevent ingestion of the main working fluid therein during operation, and should be shielded from direct exposure to these fluids. Sealing devices may be utilized to shield rotor components from leakage of the main working fluid driving the turbine, as well as to prevent cooling fluids from escaping with the main working fluid. Typical inter-stage sealing arrangements can reduce the efficiency and performance of turbines due to leakage. Leakages in inter-stage sealing can require an increase in the amount of parasitic fluid used for cooling. For example, various wheel spaces in gas turbine assemblies using typical inter-stage sealing arrangements can consume up to 50% of the total cooling air flow for cooling.